For example, a film capacitor includes a metallic membrane as an electrode which is formed on a surface of a dielectric film such as film form polypropylene resin by means of vapor deposition. With this construction, even if electrical short-circuiting occurs in an insulation defective area of the dielectric film, the metallic membrane located around the defective area is vaporized for release under energy of short-circuiting with consequent electrical isolation, thus affording the advantage of protecting the film capacitor from an electrical breakdown (for example, refer to Patent Literature 1).
Such a film capacitor, being noteworthy for its capability of preventing ignition and electric shock entailed by short-circuiting of an electric circuit, has recently been finding widespread applications including an application of film capacitors to a power supply circuit of LED (Light Emitting Diode) illumination, for example (for example, refer to Patent Literature 2).
However, on a substrate on which are mounted various electronic components, a film capacitor is still made of large size as compared with other electronic component such as a ceramic capacitor, and its large size constitutes an impediment to accomplishment of low-profile design and higher packaging density in the substrate. Therefore, studies have been carried out on development of a smaller film capacitor.
In this case, a film capacitor can be downsized by thinning of a film which is a dielectric, or by a reduction in the number of layers or convolutions of the film. However, to achieve this, improvements in relative permittivity and breakdown field strength in the film is necessary.
For example, in Patent Literature 3, there is proposed application of a dielectric film made of an organic resin with an epoxy group that contains ceramic fillers in a dispersed state to the film.